Thin-well microplate and methods of making same

ABSTRACT

A thin-well microplate and methods of manufacturing same are provided, wherein the thin-well microplate is conducive for use with automated equipment, such as robotic handling equipment, and in high temperature procedures, such as thermal cycling. The thin-well microplate is constructed of two components including a skirt and frame portion and a well and deck portion with a plurality of sample wells; both portions being joined to form a unitary microplate. Each of the skirt and frame and well and deck portions is constructed of a suitable material that imparts a specific combination of physical and material properties to the thin-well microplate. The skirt and frame portion and the well and deck portion are each constructed of the material that will allow each portion to withstand high temperature conditions and use of automated equipment, while retaining the physical characteristics each portion requires for optimal performance of the thin-well microplate. Such physical characteristics include, although not limited to, rigidity of the skirt and frame portion and thin-walled sample wells of the well and deck portion to permit optimal thermal transfer and biocompatibility. Methods of construction include forming the thin-well microplate as a unitary plate in a single, two-step process, wherein the skirt and frame portion is constructed of a suitable first material in a first step and the deck and frame portion is formed integral with the skirt and frame portion in a second step of a suitable second material. The unitary thin-well microplate plate is thereby formned of two materials for the required specific combination of physical and material properties. Another method of construction includes forming the unitary thin-well microplate in two separate manufacturing processes, wherein the skirt and frame portion is constructed of the first material in a first process and the deck and well portion constructed of the second material in a second process, and the skirt and frame portion and the well and deck portion are, thereafter, permanently joined by an adhesive system to form the unitary plate of the invention.

CLAIM OF PRIORITY

[0001] This application is a divisional patent application of U.S.nonprovisional patent application Ser. No. 09/619,116, issued as U.S.Pat. No. 6,340,589, on Jan. 22, 2002, which claims priority under 35U.S.C. §119(e) to U.S. provisional patent application Ser. No.60/145,381, filed on Jul. 23, 1999, which are incorporated herein byreference.

FIELD OF THE INVENTION

[0002] The invention provides a thin-well microplate having an array ofsample wells and a combination of specific physical and materialproperties required for use with automated equipment, such as robotichandling equipment, to withstand conditions of thermal cyclingprocedures and provide optimal thermal transfer and biologicalproperties. The invention also provides methods of constructing thethin-well microplate as a unitary plate, employing ideal materials ofconstruction to impart and optimize specific physical and materialproperties of the thin-well microplate.

BACKGROUND OF THE INVENTION

[0003] Various biological research and clinical diagnostic proceduresand techniques require or are facilitated by an array of wells or tubesin which multiple samples are disposed for qualitative and quantitativeassays or for sample storage and retrieval. Prior art devices thatprovide an array of wells or tubes capable of containing small samplevolumes include microtitration plates that are commonly known asmulti-well plates.

[0004] Multi-well plates have open-top wells, cups or recesses capableof containing small volumes of typically aqueous samples ranging fromfractions of a microliter to hundreds of microliters. Multi-well platesalso typically include sample well arrays totaling 96 sample wells thatare arranged in an array of 8 by 12 sample wells and havecenter-to-center well spacing of 9 mm, such as the multi-well platedisclosed in U.S. Pat. No. 3,356,462. Sample well arrays also includearrays of 384 wells arranged in 16 by 24 array with a reducedcenter-to-center well spacing of 4.5 mm. Well arrays are not limited toany particular number of wells nor to any specific array pattern. Forexample, U.S. Pat. No. 5,910,287 discloses a multi-well plate comprisinga well array of more than 864 wells.

[0005] Research techniques that use multi-well plates include, but arenot limited to, quantitative binding assays, such as radioimmunoassay(RIA) or enzyme-linked immunosorbant assay (ELISA), combinatorialchemistry, cell-based assays, thermal cycle DNA sequencing andpolymerase chain reaction (PCR), both of which amplify a specific DNAsequence using a series of thermal cycles. Each of these techniquesmakes specific demands on the physical and material properties andsurface characteristics of the sample wells. For instance, RIA and ELISArequire surfaces with high protein binding; combinatorial chemistryrequires great chemical and thermal resistance; cell-based assaysrequire surfaces compatible with sterilization and cell attachment, aswell as good transparency; and thermal cycling requires low protein andDNA binding, good thermal conductivity, and moderate thermal resistance.

[0006] Different uses of multi-well plates make different demands on theoverall form and structure of the multi-well plate. The compatibility ofplates with automated equipment is perhaps one of the most stringentconstraints on the form and structure of plates. Many laboratoriesautomate various steps or phases of procedures, such as depositing andremoving small quantities of reaction mixture from sample wells, often 5μl or less, using automated dispensing/aspiration systems. Furthermore,plate handling equipment is often used to help facilitate the automationof such procedures. Accordingly, it is desirable to use a multi-wellplate that is conducive to use with robotic equipment and can withstandrobotic gripping and manipulation.

[0007] Efforts to standardize the features which permit successfuldeployment of multi-well plates in robotic handling and liquid handlinginstruments have been recommended (Society of Biomolecular ScreeningRecommended Microplate Specifications http://sbsonline.com/sbs070.htm),and significant effort has been made to achieve a common geometry of keyelements of multi-well plate design, including footprint (defined aslength and width at the base plane), well location with respect to theexterior of the footprint, and overall flatness as well as rigidity inthe robotic gripping area.

[0008] Multi-well plates used in thermal cycling procedures form asub-set of multi-well plates and may be referred to as thin-wellmicroplates. Use in thermal cycling places additional material andstructural requirements on the thin-well microplates. Typically,multi-well plates are not exposed to high temperatures or to rapidtemperature cycling. Thin-well microplates are designed to accommodatethe stringent requirements of thermal cycling. For example, thin-wellmicroplates typically have design adaptations that are intended toimprove thermal transfer to samples contained within sample wells.Sample wells of thin-well microplates have thin walls typically on theorder of less than or equal to 0.015 inch (0.38 mm). Sample wellstypically are conical shaped to allow wells to nest into correspondingconical shapes of heating/cooling blocks of thermal cyclers. The nestingfeature of sample wells helps to increase surface area of thin-wellmicroplates while in contact with heating/cooling blocks and, thus,helps to facilitate heating and cooling of samples.

[0009] As described above with respect to standard multi-well plateapplications, many laboratories utilizing thin-well microplates nowautomate procedures performed prior to and subsequent to thermal cyclingand employ robotic equipment to facilitate such automation. To ensurereliable and accurate use with robotic instruments, the subset ofthin-well microplates must also possess general physical and materialproperties which facilitate robotic handling as well as enable thin-wellmicroplates to retain their dimensional stability and integrity whenexposed to high temperatures of thermal cycling.

[0010] Thin-well microplates require a specific combination of physicaland material properties for optimal robotic manipulation, liquidhandling, and thermal cycling. These properties consist of rigidity,strength and straightness required for robotic plate manipulation;flatness of sample well arrays required for accurate and reliable liquidsample handling; physical and dimensional stability and integrity duringand following exposure to temperatures approaching 100° C.; andthin-walled sample wells required for optimal thermal transfer tosamples. These various properties tend to be contradictory. For instancepolymers offering improved rigidity and/or stability typically do notpossess the material properties required to be biologically compatibleand/or to form thin-walled sample tubes. Existing thin-well microplatesare not constructed to impart all of these properties.

[0011] The typical manufacturing process for multi-well plates ispolymer injection molding due to the economy of such processes. Toinsure multi-well plates consistently adhere to specifications forrigidity and flatness, manufacturers of prior art multi-well platesemploy one or both of two design options, namely incorporatingstructural features with multi-well plates and using suitable andeconomical polymers to construct multi-well plates.

[0012] The first option of incorporating structural features withmulti-well plates includes incorporating ribs with the undersides ofmulti-well plates to reinforce flatness and rigidity. However, suchstructural features cannot be incorporated with thin-well microplatesused in thermal cycling procedures. Such structural features would notallow samples wells to nest in wells of thermal cycler blocks and,therefore, would prevent effective coupling with block wells resultingin less effective thermal transfer to samples contained within samplewells.

[0013] The second option to enhance rigidity and flatness of multi-wellplates includes using suitable, economical polymers that impart rigidityand flatness to the plates. Simultaneously the selected polymer mustalso meet the physical and material property requirements of thin-wellmicroplate sample wells in order for such sample wells to correctlyfunction during thermal cycling. Many prior art multi-well plates areconstructed of polystyrene or polycarbonate. Polystyrene andpolycarbonate resins exhibit mold-flow properties that are unsuitablefor forming the thin walls of sample wells that are required ofthin-well microplates. Molded polystyrene softens or melts when exposedto temperatures routinely used for thermal cycling procedures.Therefore, such polymer resins are not suitable for construction ofthin-well microplates for thermal cycling procedures.

[0014] Prior art thin-well microplates are also typically manufacturedby injection molding processes, wherein the entire microplate isconstructed in a single manufacturing operation of a single material,typically polypropylene or polyolefin. Construction of thin-wellmicroplates by injection molding polypropylene is desirable because theflow properties of molten polypropylene allow consistent molding of asample well with a wall that is sufficiently thin to promote optimalheat transfer when the sample well array is mounted on a thermal cyclerblock. In addition, polypropylene does not soften or melt when exposedto high temperatures of thermal cycling. However, prior art thin-wellmicroplates constructed of a single polymer resin, such as polypropyleneand polyolefin, in a single manufacturing operation possess inherentinternal stresses found in molded parts with complex features andexhibit thick and thin cross sectional portions throughout the body ofthe plate. Internal stresses result from differences in cooling rate ofthick and thin portions of the plate body after a molding process iscomplete. In addition, further distortions, such as warping andshrinkage due to internal stresses, can result when thin-wellmicroplates are exposed to conditions of thermal cycling procedures.Also, the resultant dimensional variations in flatness and footprintsize can lead to unreliable sample loading and sample recovery byautomated equipment.

[0015] Alternative prior art manufacturing methods include thermoformingthin-well multi-well plates from polycarbonate sheet material, such asproduct number 9332 available from Corning of Corning, N.Y. and productnumber CON-9601 from MJ Research, Inc. of Waltham, Mass. Thin-wellmicroplates manufactured by thermoforming polycarbonate, however, do notprovide the rigidity and dimensional precision required of thin-wellmicroplates for use with robotic equipment, nor the dimensionalprecision required for accurate liquid dispensing and aspiration byautomated sample handling equipment.

[0016] Prior art thin-well polycarbonate microplates that have beenpromoted for robotic applications continue to exhibit dimensionalvariations associated with thin-well polypropylene microplates. Suchthin-well polypropylene microplates thus limit the reliability andprecision with which such microplates may be used with roboticequipment. In addition, such thin-well polypropylene microplates requireexternal rigid adaptors to restore dimensional precision, such asMicroseal 384 Plate Positioner, product number ADR-3841 available fromMJ Research, Inc. of Waltham, Mass. Attempts to increase thin-wellmicroplate rigidity by increasing overall thickness of molded parts ofsuch microplates have resulted in an undesirable increase in thethickness of sample well walls, such as UNI PCR 96-well plate availablefrom Polyfiltronics, Inc. of Rockland, Mass., wherein the average samplewell wall thickness is greater than or equal to 0.020 inches (0.5 mm).

[0017] Using currently available manufacturing methods, the requirementsfor robotic-compatible thin-well microplates are in direct conflict withthe requirements for thin-well microplates for use in thermal cyclingprocedures. One known method of addressing this problem is to utilize atray of a first material with sample wells separately created from asecond material. Such microplates are commercially available are underthe names of “Omni-Tube Plate” and “Thermo-Tube Plate”, available fromABgene Ltd. of Surrey, UK. Both products consist of a tray, with overalldimensions approximating those of a multi-well plate, having an array ofholes into which separately manufactured tubes or strips of tubes areloosely inserted. Because of the assembly required, these products donot offer the convenience of a single, unitary plate provided by athin-well microplate. The high throughput nature of automated microplateprocesses inherently requires that manual intervention be minimized.Such a high throughput nature also precludes any preparatory orassembling steps, such as assembly of a sample vessel or microplate fromvarious component parts. Further, the geometry and loosely fittingnature of these products does not lend these products to use withhigh-precision robotic equipment and automated dispensing equipment.

[0018] Therefore, it is desirable to provide a thin-well microplate as asingle, unitary plate that is compatible for use with high-precisionrobotic handling equipment in automated procedures. A thin-wellmicroplate that possesses the physical and material properties tomaintain dimensional stability and integrity during robotic handlingunder the high temperature conditions of the thermal cycling procedureswhile also possessing properties that are conducive to thermal cyclingreactions is also highly desirable.

SUMMARY OF THE INVENTION

[0019] Embodiments of the invention are directed to a thin-wellmicroplate for use in research procedures and diagnostic techniques andto methods of manufacturing same. The thin-well microplate of theinvention comprises a unitary plate of two separate components includinga skirt and frame portion and a well and deck portion having a pluralityof sample wells. Each portion is constructed as a separate component ofa suitable material that is selected for the specific physical andmaterial properties such material imparts to each component. The skirtand frame portion and the well and deck portion are joined to form theunitary plate. The combination of physical and material propertiesprovided by the skirt and frame portion and the well and deck portionincludes, although not limited to, thin-walled sample wells for adequatethermal transfer and physical stability to withstand high temperatureconditions. The combination of physical and material properties providedby the skirt and frame portion and the well and deck portion optimizesthe performance of the thin-well microplate with automated equipment inthermal cycling procedures.

[0020] In a first embodiment of the invention, a thin-well microplateincludes a skirt and frame portion with a top surface having anplurality of holes arranged in a first array pattern and a well and deckportion joined to the top surface of the skirt and frame portion to forma unitary plate. The well and deck portion includes a plurality ofsample wells integral with the deck and portion and arranged in thefirst array pattern such that the sample wells extend through theplurality of holes of the skirt and frame portion when the well and deckportion is joined with the skirt and frame portion to form the unitaryplate. The skirt and frame portion is constructed of a first materialthat imparts rigidity to the skirt and frame portion to allow thethin-well microplate to be used with automated equipment. The well anddeck portion is constructed of a second material that forms sample wellswith thin walls of consistent thickness to allow adequate thermaltransfer to the sample wells. The second material of constructionfurther allows the thin-well microplate to be used with opticaldetection equipment due to sufficient opacity provided by the secondmaterial to the sample wells.

[0021] The unitary plate of the first embodiment includes the skirt andframe portion and the well and deck portion formed as separatecomponents and then permanently joined to form the unitary plate. Inanother version of the first embodiment, the well and deck portion isformed integral with the top surface of the skirt and frame portion toform the unitary plate.

[0022] The skirt and frame portion includes four walls forming a bottomopposite the top surface, wherein the bottom has a length and widthslightly larger than the length and width of the top surface. The skirtand frame portion further includes at least one indentation in each wallto allow engagement of automated equipment with the thin-wellmicroplate.

[0023] The well and deck portion further includes a raised rim around anopening of each sample well that is contiguous with an upper surface ofthe well and deck portion. The raised rim forms grooves in the well anddeck portion between adjacent sample wells to prevent contaminationbetween sample wells.

[0024] In another embodiment of the invention, the well and deck portionincludes an upper surface having a plurality of interconnecting linkswith individual links joining adjacent sample wells to form a meshworkof interconnecting links and sample wells. As described above, the welland deck portion including the meshwork of interconnecting links andsample wells may be formed as a separate component of the skirt andframe portion and then permanently joined to the skirt and frame portionto form the unitary plate. Alternatively, in a version of thisembodiment, the meshwork may be formed integral with the top surface ofthe skirt and frame portion.

[0025] In still another embodiment of the invention, the thin-wellmicroplate includes a skirt and frame portion, constructed of a firstmaterial, having a top surface with a plurality of holes arranged in afirst array pattern, and walls of equal depth extending from the topsurface. The skirt and frame portion further includes a plurality ofsample wells, constructed of a second material, and arranged in thefirst pattern such that the sample wells extend through the plurality ofholes in the top surface of the skirt and frame portion. In a version ofthis embodiment, the thin-well microplate includes a plurality ofinterconnecting links with individual links joining adjacent samplewells.

[0026] In the first embodiment, the first material used to construct theskirt and frame portion is, although not limited to, a polymer resin ora filled polymer resin. The filled polymer resin is capable ofwithstanding a temperature of at least 100° C. which allows thethin-well microplate to be used in thermal cycling procedures in whichhigh temperatures are used. The skirt and frame portion in one versionof the first embodiment is constructed of glass-filled polypropylenewhich imparts sufficient rigidity to the skirt and frame portion toallow the thin-well microplate to be used with automated equipment.

[0027] The second material used to construct the well and deck portionof the first embodiment is, although not limited to, a polymer resin oran unfilled polymer resin. The unfilled polymer resin is capable ofwithstanding a temperature of at least 100° C., which similarly allowsthe thin-well microplate to be used in high temperature thermal cyclingprocedures. However, the unfilled polymer resin not only withstands hightemperature conditions of thermal cycling, but forms sample wells withthin walls of consistent thickness. In one version of this embodiment,the well and deck portion is constructed of an unfilled polypropylenewhich forms sample wells with thin walls to allow adequate thermaltransfer to sample wells during thermal cycling procedures, and alsoprovides sufficient opacity to the sample wells to allow use of opticaldetection equipment with the thin-well microplate.

[0028] The invention is also directed to methods of construction of thethin-well microplate. Methods of construction include in one embodimenta first method of construction wherein the thin-well microplate isformed as a unitary plate in a single molding process comprising twosteps. The first method of construction includes providing a firstmaterial that is conducive to the molding process, and molding an insertof the first material in a first step, wherein the insert includes aplurality of holes formed in a top surface of the insert. The firstmethod of construction further includes providing a second material thatis conducive to the molding process, positioning the insert to receivethe second material and applying the second material to the insert in asecond step, wherein an over-mold is molded having a planar deckintegrally formed with a top surface of the insert and a plurality ofsample wells integrally formed with the top surface of the insert andthe plurality of holes to produce the unitary plate.

[0029] In a version of this embodiment, the molding process is aninjection molding process including the first step as a first injectionmolding of the first material and the second step as a second injectionmolding of the second material. In other versions of this embodiment,the first and second materials are polymer resins, or, alternatively,the first material is a glass-filled polypropylene and the secondmaterial is an unfilled polypropylene.

[0030] Another embodiment of the methods of construction includes asecond method of construction, wherein the thin-well microplate isformed as a unitary plate in two separate manufacturing processes. Thesecond method of construction includes providing a first material thatis conducive to a first manufacturing process, forming a skirt and frameportion of the first material by the first manufacturing process,wherein the skirt and frame portion includes a plurality of holes formedin a top surface of the skirt and frame portion. The second method ofconstruction further includes providing a second material that isconducive to a second manufacturing process and forming a well and deckportion of the second material by the second manufacturing process,wherein the well and deck portion includes a plurality of sample wellsformed in a top planar deck of the well and deck portion that are sizedfor insertion into the plurality of holes of the skirt and frameportion. According to the second method of construction, the skirt andframe portion and the well and deck portion are joined after theirseparate manufacture such that the plurality of sample wells is disposedin the plurality of holes. The well and deck portion is permanentlyadhered to the top surface of the skirt and frame portion to produce theunitary plate.

[0031] In a version of the second method of construction of thethin-well microplate, the first and second manufacturing processes arenot only separate processes, but different methods of construction. Thefirst and the second manufacturing processes may be different methods ofmolding, for instance, wherein the first manufacturing process is aconvention molding process and the second manufacturing process is aninjection molding process. Alternatively, in another version of thesecond embodiment, the first and the second manufacturing processes aresimilar methods of manufacturing.

[0032] The second method of construction of the thin-well microplateallows the first and second manufacturing processes to each employdifferent materials of construction. Accordingly, another version ofthis embodiment includes, for instance, the first manufacturing processemploying a glass-filled polypropylene to form the skirt and frameportion and the second manufacturing process employing an unfilledpolypropylene to form the well and deck portion, thereby forming aunitary plate constructed of two different materials. Still anotherversion of this embodiment of constructing the thin-well microplate intwo separate manufacturing processes includes constructing the skirt andframe portion in the first manufacturing process of the first materialthat is a material other than a polymer resin, such as aluminum sheetstock, and constructing the well and deck portion in the secondmanufacturing process of the second material including an unfilledpolypropylene.

[0033] Although the second method of construction of the thin-wellmicroplate includes using different materials in each of two differentor similar, but separate, processes, to construct the skirt and frameportion and the well and deck portions as separate components, the skirtand frame portion and the well and deck portion are thereafterpermanently joined by adhering steps that may include, for instance,ultrasonic or thermal welding, to form the unitary plate of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] For a better understanding of the invention, reference is made tothe drawings which are incorporated herein by reference and in which:

[0035]FIG. 1 is a perspective view of a thin-well microplate accordingto an embodiment of the invention.

[0036]FIG. 2a is a top view of a skirt and frame portion of themicroplate of FIG. 1.

[0037]FIG. 2b is a side view of a side wall of the skirt and frameportion of the microplate of FIG. 1.

[0038]FIG. 2c is a side view of an end wall of the skirt and frameportion of the microplate of FIG. 1.

[0039]FIG. 3a is a top view of a well and deck portion of the microplateof FIG. 1.

[0040]FIG. 3b is a side view of the well and deck portion of themicroplate of FIG. 1.

[0041]FIG. 3c is a cross-sectional side view of an array of sample wellsof the microplate of FIG. 1.

[0042]FIG. 4 is a cross-sectional side view of the array of sample wellsdisposed on the skirt and frame portion.

[0043]FIG. 5 is a cross-sectional side view of the array of sample wellsof a second embodiment of the invention.

[0044]FIG. 6 is a top view of the array of sample wells of a thirdembodiment of the invention.

[0045]FIG. 7 is a process flow diagram illustrating a first method ofconstruction of a microplate of the present invention.

[0046]FIG. 8 is a process flow diagram illustrating an embodiment of thefirst method of construction.

[0047]FIG. 9 is a process flow diagram illustrating a second method ofconstruction of a microplate of the present invention.

[0048]FIG. 10 is a process flow diagram illustrating an embodiment ofthe second method of construction.

DETAILED DESCRIPTION OF THE INVENTION

[0049] Illustrative embodiments of the invention described below aredirected to a thin-well microplate, and methods for manufacturing thesame, for use in research procedures and diagnostic techniques thatrequire or desire multiple samples for qualitative and quantitativeanalyses. More specifically, the invention is directed to a thin-wellmicroplate with thin-walled sample wells and a specific combination ofphysical and material properties such that the microplate isparticularly suited for use in thermal cycling procedures and withautomated equipment. Those skilled in the art will appreciate, however,that embodiments of the invention are not limited to the thin-wellmicroplate for use in thermal cycling applications, but, rather, mayinclude the thin-well microplate for sample containment and storage fora variety of reactions and assays. The invention is also directed towardmethods of constructing the thin-well microplate as a unitary plate withthe specific combination of physical and material properties that areconducive for use with automated equipment and in thermal cyclingprocedures.

[0050] Embodiments of the invention will be described with reference toFIGS. 1-10 which are presented for the purpose of illustratingembodiments and are not intended to limit the scope of the claims.

[0051] Referring to FIGS. 1 and 2a-2 c, a first embodiment of theinvention includes a unitary thin-well microplate 10 including twojoined components, a skirt and frame portion 11 and a well and deckportion 12 on the skirt and frame portion 11 to form the thin-wellmicroplate 10. Depending upon methods of construction discussed below,the well and deck portion 12 is formed integral with the skirt and frameportion 11, or, alternatively, formed separately from the skirt andframe 11 and thereafter permanently assembled with the skirt and frameportion 11 to form the thin-well microplate 10 as a single unitarymicroplate.

[0052] The skirt and frame portion 11 includes a top rectangular planarsurface 15 and a bottom 16. The top planar surface 15 is connected tothe bottom 16 by four walls, including two end walls 17 a, 17 b and twoside walls 17 c, 17 d. The top planar surface 15 has a length L₁ ofabout 122 mm, and a width W₁ of about 78 mm. The bottom 16, as formed bythe end walls 17 a, 17 b, and side walls 17 c, 17 d, includes dimensionsthat are slightly larger than the dimensions of the top planar surface15 to extend the bottom 16 beyond a perimeter of the top planar surface15. The bottom 16 has a length L₂ of about 127mm and a width W₂ of about85 mm. The skirt and frame portion 11 of the first embodiment isrectangular in shape, although it is understood by those skilled in theart that the skirt and frame portion 11 is not limited to a specificshape and may include other shapes and overall dimensions.

[0053] The top planar surface 15 includes an array of holes 13 formedtherein and integral with the top surface 15 to accommodate acorresponding array of sample wells, or a well-array. In the firstembodiment illustrated in FIG. 1, the array of holes 13 (only part ofwhich are shown) is arranged in a rectangular pattern that includes atotal of 384 holes, arranged in an array of 16 by 24 holes capable ofreceiving a 384-well array of sample wells. In another embodiment, thetop planar surface 15 may include the array of holes 13 with a total of96 holes arranged in an array of 8 by 12 holes capable of receiving a96-well array of sample wells. Although the array of holes 13 of thefirst embodiment illustrated in FIG. 1 is structured and configured toaccommodate a 384-well array of sample wells, it is understood by thoseskilled in the art that the array of holes 13 in the top surface 15 mayinclude any number of holes to accommodate well arrays of higher orlower sample well density, and may be arranged in alternative arraypatterns.

[0054] Referring to FIG. 2a, individual holes of the 384-hole array 13have a circular opening 20 integral with the top planar surface 15. Asshown in FIGS. 1 and 2a-2 c, the end walls 17 a, 17 b of the skirt andframe portion 11 each include a pair of indented notches formed thereinand referred to as index points 18 a, 18 b. Each of the side walls 17 c,17 d similarly includes a pair of index points 18 c, 18 d formedtherein. The pairs of index points 18 a, 18 b, 18 c, 18 d are structuredand configured to receive engagement mechanisms of automated handlingequipment, such as, but not limited to, a robotic arm, and help suchengagement mechanisms to grip and transport the skirt and frame portion11 and to facilitate accurate and consistent placement of the thin-wellmicroplate 10 during the automated phases of liquid sample handlingprocedures. In the first embodiment illustrated in FIGS. 2a-2 c, thepairs of index points 18 a, 18 b, 18 c, 18 d are rectangular shaped,although they are not limited to a particular shape or configuration andmay include other geometries and shapes necessary to receive engagementmechanisms of automated equipment.

[0055] The skirt and frame portion 11 of the thin-well microplate 10 isconstructed of a suitable material that imparts and optimizes thephysical and material properties of strength and rigidity to the skirtand frame portion 11, as well as straightness to the top planar surface15 and bottom 16. In addition to structural strength, rigidity andstraightness, a suitable material of construction imparts dimensionalstability to the skirt and frame portion 11 and resists shrinkage anddistortion of the physical geometry and the overall dimensions that mayresult from exposure to high temperatures of thermal cycling processesduring use. A suitable material of construction also substantiallyresists deformation of the skirt and frame portion 11 caused by grippingand holding of engagement mechanisms of automatic handling equipment,such as a robotic arm, with the skirt and frame portion 11.

[0056] A suitable material of construction of the skirt and frameportion 11 includes, but is not limited to, a polymer resin, such as aglass-filled polypropylene including, for example, AMCO #PP1015Gglass-filled polypropylene available from AMCO International, Inc. ofFarmingdale, N.Y. AMCO #PP1015G glass-filled polypropylene has astandard melting point of approximately 170° C. and is substantiallyresistant to excessive softening due to cyclic exposure to hightemperatures of thermal cycling processes, typically about 80° C. toabout 96° C., and often up to about 100° C. Filled polypropylenepossesses suitable flow characteristics, e.g.: melt flow of 4-8 g/min,that render such material conducive to manufacturing the skirt and frameportion 11 by various molding processes described herein. Filledpolymers minimize or eliminate the need to add other physicalmechanisms, such as strengthening ribs, to the skirt and frame portion11 to enhance strength and rigidity. While it is desirable to mold theskirt and frame portion 11 of a glass filled polypropylene it should benoted that other filled polymers may be utilized to produce acceptableresults. Examples of these are various families of filledpolypropylenes, for instance 20% to 40% talc filled or 40% to 60%calcium carbonate filled, all available from AMCO International, Inc.Further examples of acceptable polymers include several of those in theamorphous polymer family, such as glass filled polycarbonate

[0057] Referring to FIGS. 1, 3a-3 c, the well and deck portion 12 of thethin-well microplate 10 includes a rectangular planar deck 19 with a topsurface 30 and a bottom surface 31. The planar deck 19 has a length L₃of about 119.93 to about 120.03 mm, and a width W₃ of about 78.33 mm toabout 78.43 mm. The planar deck 19 of the first embodiment isrectangular in shape, although it is understood by those skilled in theart that the invention is not limited to the planar deck 19 of aspecific shape and may include other shapes and overall dimensions.

[0058] The planar deck 19 includes an array of sample wells 14 formedintegral with the planar deck 19. The array of sample wells 14 isarranged in a rectangular pattern and includes a number and pattern ofsample wells that corresponds to the number and pattern of the array ofholes 13 of the skirt and frame portion 11 such that the array of samplewells 14 is coupled with the array of holes 13 of the skirt and frameportion 11. The array of sample wells 14 of the first embodimentillustrated in FIG. 1 includes a total of 384 sample wells 14 arrangedin an array of 16 by 24 sample wells 14. In another embodiment, theplanar deck 19 includes the array of sample wells 14 with a total of 96sample wells arranged in an array of 8 by 12 sample wells 14. In thefirst embodiment, the center-to-center spacing between individual samplewells 14 is about 4.5 mm.

[0059] Although the 384-well array of sample wells 14 is illustrated inFIG. 1, it is understood by those skilled in the art that the planardeck 19 may include sample well arrays 14 of higher or lower welldensity as well as arrays of sample wells configured in alternativepatterns. The center-to-center is preferably maintained at about 9 mm orsome integral fraction or multiple thereof to allow the use of standardautomated equipment for processing samples, as such standard equipmentis designed for 9 mm center-to-center spacing of sample wells. Whenother automated equipment is used the center-to-center spacing may bedifferent to conform with such equipment.

[0060] As shown in FIGS. 3a and 3 c, individual sample wells 14 of thefirst embodiment include an opening 32 in the top surface 30 of theplanar deck 19 having a diameter D_(S) of about 3.12 mm to about 3.22mm. Individual sample wells 14 are sized for insertion or formation intoindividual holes 13 of the array of holes 13 in the skirt and frameportion 11. Individual sample wells 14 include a well body 33 thatextends downwardly from the opening 32 and a raised rim 34 surroundingeach well opening 32. The raised rim 34 creates a recessed area betweenadjacent sample wells 14 to reduce the possibility of contaminationbetween wells. The sample well body 33 is conically-shaped and has adepth D₂ of about 15.5 mm. Side walls 14 a of the conically-shaped wellbody 33 angle inward about 17.1° to about 17.9° and narrow to a diameterof about 1.66 mm to about 1.76 mm. Although the first embodiment ofsample wells 14 illustrated in FIGS. 3a-3 c include the shape anddimensions described above, it is understood by those skilled in the artthat the samples wells may include other shapes and dimensions.

[0061] The side walls 14 a of individual sample wells 14 are thin,having a thickness of, although not limited to, about 0.15 mm to about0.25 mm. Individual sample wells 14 have a flat, thin bottom wall 14 bhaving a thickness of, although not limited to, about 0.15 mm to about0.25 mm. When the well and deck portion 12 is engaged with or integralto the skirt and frame portion 11, as illustrated in FIG. 4, the lowerportion of walls 14 a of the array of sample wells 14 can be in intimatecontact with wells of a heating/cooling block of a thermal cycler deviceused during thermal cycling to expose samples to heat. The thin natureof the sample well walls 14 a and the bottom walls 14 b helps tofacilitate adequate thermal transfer to samples contained within thesample wells 14.

[0062] A suitable material of construction of the well and deck portion12 includes, but is not limited to, a polymer resin, such as a virgin,unfilled polypropylene including, for example, FINA #3829 polypropylene,available from AMCO International, Inc. of Farmingdale, N.Y. FINA #3829polypropylene has a standard melting point of approximately 170° C. FINA#3829 polypropylene possesses a high melt flow rate, such as 6 g/min,which renders such material conducive to construction by various moldingprocesses described herein. In addition, the FINA family ofpolypropylenes possess high deflection temperatures enabling suchmaterial to withstand high temperatures of thermal cycling.

[0063] The skirt and frame portion 11 is constructed of a first suitablematerial that imparts and maintains during thermal cycling proceduresthe physical and material properties of opacity, strength and rigidity.The well and deck portion 12 is constructed of a second suitablematerial that permits the sample well walls 14 a and 14 b to be thinlyconstructed of a thickness of about 0.15 mm to about 0.38 mm. A suitablematerial of construction also reduces or eliminates variation in wellwall thickness throughout the sample well body 33 and between individualsample wells 14 during manufacture of the well and deck portion 12. Theuse of separate materials for the skirt and frame portion 11 and thewell and deck portion 12 of microplate 10 allows optimization ofproduction processes not possible when molding multi-well plates of asingle resin in one operation. Thus, the multi-well microplate 10 isless susceptible to warping after thermal cycling. In addition, theconstruction of microplate 10 allows for use a suitable material forwell and deck portion 12 that is compatible with biomolecules andpossesses good clarity to allow optical analysis of samples, whileallowing for use of a suitable material for skirt and deck portion 11that may not be biocompatible or optically clear but may possess theproperties of strength, rigidity and stability

[0064] Referring to FIG. 5, in a second embodiment of the invention, thearray of sample wells 14 is formed without the planar deck 19 acting asa connecting structure between individual sample wells 14. Rather,sample wells 14 are formed as independent and separate wells integralwith the skirt and frame portion 11 without any connection means betweenadjacent sample wells.

[0065] Referring to FIG. 6, in a third embodiment of the invention, thearray of sample wells 14 is similarly formed without the planar decks 19and 15 but with interconnecting links 42 between adjacent sample wells14, forming a meshwork of links 42 that acts as a connecting meansbetween individual sample wells 14. In this embodiment, the meshwork oflinks 42 and interconnected sample wells 14 is fabricated to or formedinto the skirt and frame portion 11.

[0066] The thin-well microplate 10 of the invention and methods ofmaking same described below simultaneously combine many desirablefeatures thus providing several advantages over prior art microplates.The thin-well microplate 10 possesses the physical and materialproperties that render the microplate 10 capable of withstanding hightemperature conditions of thermal cycling procedures and conducive foruse with automated equipment, particularly robotic handling instruments.The thin-well microplate 10 also maintains a compatibility with standardautomated liquid handling equipment, such as the Hydra™ dispensingsystem available from Robbins Scientific of Sunnyvale, Calif., forintroducing and removing sample mixtures from sample wells. The samplewells 14 of the thin-well microplate 10 are relatively thin, on theorder of 0.25 mm or less, which helps facilitate optimal thermaltransfer to samples during thermal cycling procedures. In addition, thethickness of sample well walls 14 a, 14 b permits use of opticaldetection systems for optically analyzing samples through sample wellbottoms.

[0067] Methods of construction of the thin-well microplate 10 of theinvention include manufacturing the skirt and frame portion 11 and thewell and deck portion 12 separately, either by different steps of asingle manufacturing process or by separate manufacturing operations.Such methods of construction provide the advantage of constructing eachportion of an ideal material that will impart and maintain the optimalphysical and material properties required and desired of the thin-wellmicroplate 10. The invention provides the thin-well microplate 10 with aspecific combination of physical and material properties includingstrength, rigidity, and straightness of the skirt and frame portion 11to withstand manipulation by automated equipment; dimensional stabilityand integrity of the skirt and frame portion 11 and the well and deckportion 12 during and following exposure to the high temperatures ofthermal cycling procedures; substantial flatness of the array of samplewells 14 for accurate and reliable handling of liquid samples; andthin-walled sample wells 14 to help optimize thermal transfer and topermit optical analysis. Prior art methods of constructing thin-wellmicroplates do not use materials or processes that produce thin-walledmulti-well microplates that possess the combination of specific physicaland material properties of the present invention.

[0068] The present invention also includes methods for forming thethin-well microplate having the properties of the invention. A firstmethod for constructing the thin-well microplate 10 includesmanufacturing the thin-well microplate 10 by a single process, whereinthe well and deck portion 12 is formed integral with the skirt and frameportion 11. Each portion of the thin-well microplate 10 is manufacturedof a separate material and by a separate step of the same process toproduce a unitary plate. Referring to FIG. 7, a two-step molding processincludes providing a suitable first material in a form conducive for usein a well known molding process 410. In a first step of the moldingprocess 420, the skirt and frame portion 11 is molded of the firstmaterial as an insert. A suitable second material is provided in a formconducive for use in the well known molding process 430. The insert orthe skirt and frame portion 11 is subsequently positioned to receive anapplication of the second material 440. In a second step of the wellknown molding process 450, the well and deck portion 12 is moldedintegral with the skirt and frame portion 11 of the second suitablematerial as an over-mold, producing a unitary plate.

[0069] Referring to FIG. 8, a specific embodiment of the first method ofconstruction of the thin-well microplate, includes manufacturing thethin-well microplate 10 by a two-step molding process well known tothose skilled in the art including initially providing a first material,such as, but not limited to, a filled polymer resin, in a form conducivefor use with a well known molding process 510. In a first step of thewell known molding process 520, an insert is molded of the filledpolymer resin, to form the skirt and frame portion 11. A second materialis provided, such as, but not limited to, an unfilled polymer resin, ina form conducive for use in the well known molding process 530. In asecond step 540 of the well known molding process, the unfilled polymerresin is applied to the insert as an over-mold to form the well and deckportion producing a unitary plate. The insert or skirt and frame portion11 acts as a skeleton over which the over-mold or the well and deckportion 12 is integrally formed.

[0070] A second embodiment of the first construction method includesmanufacturing the well and deck portion 12 integral with the skirt andframe portion 11 by a single two-step injection molding process wellknown to those skilled in the art. Such a process is described inInjection Molding, Vol. 8, No. 4, Part 1 of 2, April 2000 Edition. Thetwo-step injection molding process may be performed by using variouscommercially available injection molding presses that are design fortwo-step molding processes, such as the SynErgy 2C press available fromNetstal-Maschinen AG of Naefels, Switzerland or Netstal-Machinery, Inc.of Devens, Mass. The two-step injection molding technique uses a singlemold and includes forming the skirt and frame portion 11 of the firstmaterial by a first shot injection molding in a first step. The well anddeck portion 12 is subsequently constructed of the second material by asecond shot injection into the same mold in a second step forming thearray of sample wells 14 as well as filling an area surrounding thesample wells openings 32 to form the planar deck 19.

[0071] A second method of construction of the thin-well microplate 10includes forming the skirt and frame portion 11 and the well and deckportion 12 by two separate manufacturing processes of separate materialsof construction. Referring to FIG. 9, in a first manufacturing processwell known to those skilled in the art, a first suitable material isprovided in a form conducive to the first manufacturing process 610. Theskirt and frame portion 11 is formed of the first material by the firstmanufacturing process 620. A second suitable material is provided in aform conducive to a second manufacturing process well known to thoseskilled in the art 630. A well and deck portion 12 is formed of thesecond material by the second manufacturing process 640. The skirt andframe portion 11 and the well and deck portion 12 are thereafterpermanently joined by an adhesive method well known to those skilled inthe art, such as ultrasonic welding or thermal welding, producing aunitary plate 650. The first and second manufacturing processes may bedifferent manufacturing processes or similar processes performedseparately.

[0072] Referring to FIG. 10, a version of the second method ofconstruction includes forming the skirt and frame portion 11 and thewell and deck portion 12 by separate injection molding processes oroperations. A first suitable material, such as a filled polymer resinincluding glass-filled polypropylene, is provided in a form conducive toa first injection molding process 710. The skirt and frame portion 11 ismolded of glass-filled polypropylene by the first injection moldingoperation 720. A second suitable material is provided, such as, but notlimited to, an unfilled polymer resin including unfilled polypropylene730. The well and deck portion 12 is constructed in a second andseparate injection molding manufacturing process of unfilledpolypropylene 740. The skirt and frame portion 11 and the well and deckportion 12 are thereafter permanently joined by ultrasonic welding toproduce a unitary plate 750. Ultrasonic welding may be performed byusing ultrasonic welding equipment available from Herrmann Ultrasonics,Inc. of Schaumburg, Ill.

[0073] In another version of the second method of construction, thethin-well microplate 10 is constructed by two separate methods ofconstruction with each portion manufactured by separate processes usingalternative materials of construction. For instance, the skirt and frameportion 11 is constructed of a material other than a polymer resin thatsimilarly imparts and maintains the optimal physical and materialproperties desired of the skirt and frame portion 11. Such analternative material may include, but is not limited to, aluminum sheetstock. The skirt and frame portion 11 is initially formed of aluminumsheet stock in a first process by either a stamping or electromagneticforming method well known to those skilled in the art. The skirt andframe portion 11 is then positioned in an injection mold in a secondprocess, wherein the well and deck portion 12 is constructed of apolymer resin, such as unfilled polypropylene, by an over-moldingprocess that forms the array of sample wells 14 and the planar deck 19over the skirt and frame portion 11.

[0074] Having thus described at least one illustrative embodiment of theinvention, various alterations, modifications and improvements willreadily occur to those skilled in the art. Such alterations,modifications and improvements are intended to be within the scope andspirit of the invention. Accordingly, the foregoing description is byway of example only and is not intended as limiting. The invention'slimit is defined only in the following claims and the equivalentsthereto.

What is claimed is:
 1. A thin-well microplate comprising: a skirt andframe portion, constructed of a first material, having a top surfacehaving a plurality of holes arranged in a first array pattern, and wallsof equal depth extending from the top surface; a well and deck portion,constructed of a second material, joined with the top surface of theskirt and frame portion to form a unitary plate; a plurality of samplewells integral with the well and deck portion arranged in the firstarray pattern such that the plurality of sample wells extend through theplurality of holes in the top surface of the skirt and frame portion. 2.The thin-well microplate of claim 1, wherein the first material impartsrigidity to the skirt and frame portion to allow use of automatedequipment with the thin-well microplate.
 3. The thin-well microplate ofclaim 1, wherein the second material forms the sample wells with thinwalls having a thickness appropriate to allow adequate thermal transfer.4. The thin-well microplate of claim 1, wherein the second materialforms the sample wells with sufficient opacity to allow use of opticaldetection equipment with the thin-well microplate.
 5. The thin-wellmicroplate of claim 1, wherein the skirt and frame portion and the welland deck portion are formed of separate components and permanentlyjoined to form the unitary plate.
 6. The thin-well microplate of claim1, wherein the well and deck portion is integrally formed with the topsurface of the skirt and frame portion.
 7. The thin-well microplate ofclaim 1, wherein the skirt and frame portion includes four walls forminga bottom of the skirt and frame portion opposite the top surface.
 8. Thethin-well microplate of claim 7, wherein the bottom has a length andwidth slightly larger than the length and width of the top surface. 9.The thin-well microplate of claim 1, further comprising a raised rimaround an opening of each of the sample wells which is contiguous withan upper surface of the well and deck portion.
 10. The thin-wellmicroplate of claim 9, further comprising grooves between the raisedrims of adjacent sample wells.
 11. The thin-well microplate of claim 1,further comprising at least one indentation in each wall of the skirtand frame portion for engagement of automated equipment.
 12. Thethin-well microplate of claim 1, wherein an upper surface of the welland deck portion includes a plurality of interconnecting links, eachinterconnecting link joining at least two of the plurality of samplewells.
 13. A thin-well microplate comprising: a skirt and frame portion,constructed of a first material, having a top surface having a pluralityof holes arranged in a first array pattern, and walls of equal depthextending from the top surface; a plurality of sample wells, constructedof a second material, arranged in the first array pattern such that theplurality of sample wells extend through the plurality of holes in thetop surface of the skirt and frame portion.
 14. The thin-well microplateof claim 13, further comprising a plurality of interconnecting links,each interconnecting link joining at least two of the plurality ofsample wells.
 15. The thin-well microplate of claim 1, wherein the firstmaterial is a polymer resin.
 16. The thin-well microplate of claim 1,wherein the first material is a filled polymer resin.
 17. The thin-wellmicroplate of claim 16, wherein the filled polymer resin is capable ofwithstanding a temperature of at least 100° C.
 18. The thin-wellmicroplate of claim 16, wherein the filled polymer resin is glass-filledpolypropylene.
 19. The thin-well microplate of claim 1, wherein thesecond material is a polymer resin.
 20. The thin-well microplate ofclaim 1, wherein the second material is an unfilled polymer resin. 21.The thin-well microplate of claim 20, wherein the unfilled polymer resinis capable of withstanding a temperature of at least 100° C.
 22. Thethin-well microplate of claim 20, wherein the unfilled polymer resin isunfilled polypropylene.
 23. A method of constructing a thin-wellmicroplate comprising steps of: providing a first material in a formconducive for use in a two-step molding process; molding an insert ofthe first material in a first step of the molding process, wherein theinsert includes a plurality of holes formed in a top surface of theinsert; providing a second material in a form conducive for use in themolding process; positioning the insert to receive the second material;applying the second material to the insert; and molding an over-mold ofthe second material by a second step of the molding process, wherein theover-mold is a planar deck and a plurality of sample wells integrallyformed with the top surface of the insert and the plurality of holes toproduce a unitary plate.
 24. The method of construction of the thin-wellmicroplate of claim 23, wherein the first material is a polymer resinand the second material is a polymer resin.
 25. The method ofconstruction of the thin-well microplate of claim 24, wherein the firstmaterial is a glass-filled polypropylene and the second material is anunfilled polypropylene.
 26. The method of construction of the thin-wellmicroplate of claim 23, wherein the molding process is a two-stepinjection molding process.
 27. A method of constructing a thin-wellmicroplate comprising steps of: providing a first material in a formconducive for use in a first manufacturing process; forming a skirt andframe portion of the first material by the first manufacturing process,wherein the skirt and frame portion includes a plurality of holes formedin a top planar surface of the skirt and frame portion; providing asecond material in a form conducive for use in a second manufacturingprocess; forming a well and deck portion of the second material by thesecond manufacturing process, wherein the well and deck portion includesa plurality of sample wells formed in a top planar deck of the well anddeck portion and sized for insertion into the plurality of holes of theskirt and frame portion; and joining the well and deck portion to theskirt and frame portion such that the plurality of sample wells aredisposed in the plurality of holes; and adhering the well and deckportion permanently to the top surface of the skirt and frame portion toproduce a unitary plate.
 28. The method of constructing the thin-wellmultiplate of claim 27, wherein the first and the second manufacturingprocesses are different methods of manufacturing.
 29. The method ofconstructing the thin-well multiplate of claim 27, wherein the first andthe second manufacturing processes are similar methods of manufacturing.30. The method of constructing the thin-well multiplate of claim 27,wherein the first and the second manufacturing process each include amolding process.
 31. The method of constructing the thin-well multiplateof claim 30, wherein the molding process is an injection moldingprocess.
 32. The method of constructing the thin-well multiplate ofclaim 27, wherein the first material is a polymer resin and the secondmaterial is a polymer resin.
 33. The method of constructing thethin-well multiplate of claim 32, wherein the first material is aglass-filled polypropylene and the second material is an unfilledpolypropylene.
 34. The method of constructing the thin-well multiplateof claim 27, wherein the first material is a material other than apolymer resin and the second material is a polymer resin.
 35. The methodof constructing the thin-well multiplate of claim 27, wherein theadhering step includes ultrasonic welding.
 36. The method ofconstructing the thin-well multiplate of claim 27, wherein the adheringstep includes thermal welding.